12 week undersized Buff is wasting away.

My Buff is one-third smaller than the other Buffs from birth.. She ate well, socialized well. Was not picked on and was an equal in all aspects, just smaller.

One morning chicken was lethargic, head tucked in, sickly looking. Didn't know till day two it was impacted crop. I flushed out crop, perhaps not enough water, and got green stuff out. Still had oversized crop. Day three. Flushed crop out, got way more grass blades out. Did this three times. Should mention I used warm water and baking soda. Crop still enlarged. Should mention she is isolated from the start. Didn't feed food until day three when she got some egg and yogurt and some olive oil. She ate a little bit. Seemed to like yogurt (probiotics). Her poop was all white day three. Day four no poop.

Now day four, flushed her out three times and now drainage just looks like slightly dirty water. Crop still somewhat enlarged, but less. She is very week, has a hard time standing. Will not eat yogurt. I have no more answers.........Perhaps it is time?